Dispersions comprising high surface area nanotubes and discrete carbon nanotubes

Abstract

The present application pertains to dispersions comprising oxidized, discrete carbon nanotubes and high-surface area carbon nanotubes. The oxidized, discrete carbon nanotubes comprise an interior and exterior surface, each surface comprising an interior surface oxidized species content and an exterior surface oxidized species content. The interior surface oxidized species content differs from the exterior surface oxidized species content by at least 20%, and as high as 100%. The high-surface area nanotubes are generally single-wall nanotubes. The BET surface area of the high-surface area nanotubes is from about 550 m2 / g to about 1500 m2 / g according to ASTM D6556-16. The aspect ratio is at least about 500 up to about 6000. The dispersions comprise from about 0.1 to about 30% by weight nanotubes based on the total weight of the dispersion.

Description

CROSS-REFERENCES[0001]This application is a continuation-in-part application of U.S. Ser. No. 16 / 012,265 filed Jun. 19, 2018 and issuing on Mar. 2, 2021 as U.S. Pat. No. 10,934,447. U.S. Ser. No. 16 / 012,265 is a continuation-in-part application of U.S. Ser. No. 15 / 840,174, filed on Dec. 13, 2017, and allowed on Apr. 11, 2018, and issuing as U.S. Pat. No. 10,000,653, which is a continuation of U.S. Ser. No. 15 / 496,721, filed Apr. 25, 2017, abandoned, which was a continuation-in-part application of U.S. Ser. No. 15 / 288,553 filed Oct. 7, 2016 and allowed Mar. 21, 2017 to be issued as U.S. Pat. No. 9,636,649, which was a continuation-in-part application of U.S. Ser. No. 15 / 225,215 filed Aug. 1, 2016, allowed Sep. 12, 2016 and issued as U.S. Pat. No. 9,493,626 which was a continuation-in-part application of U.S. Ser. No. 15 / 166,931 filed May 27, 2016 and issued as U.S. Pat. No. 9,422,413 which was a continuation of U.S. Ser. No. 14 / 924,246, filed Oct. 27, 2015 and issued as U.S. Pat. No....

AI Technical Summary

Benefits of technology

This patent is about improving the materials and processes used to make energy storage and collection devices like batteries, capacitors, and photovoltaics, by using high-surface area carbon nanotubes. These nanotubes are formed by fibrillating manufactured nanotubes through targeted oxidation or high energy forces. This fibrillation causes the nanotubes to loosen and expose more surface area, enhancing their interaction with the surrounding materials and improving the efficiency of the device. Overall, this patent provides a cost-effective solution for producing high-quality energy storage and collection devices.

Problems solved by technology

However, utilization of carbon nanotubes in these applications has been hampered due to the general inability to reliably produce individualized carbon nanotubes.

These tubes have low aspect ratios not suitable for high strength composite materials.

The dilution ranges are often in the mg / liter ranges and not suitable for commercial usage.

The salts for the cathode materials in lithium ion batteries are generally known to have poor electrical conductivity and poor electrochemical stability which results in poor cycling (charge / discharge) ability.

The high internal resistance of the batteries, particularly in large arrays of lithium ion batteries such as used in electric vehicles, can result in excessive heat generation leading to runaway chemical reactions and fires due to the organic liquid electrolyte.

These lithium primary batteries have excellent storage lifetimes, but suffer from only being able to provide low current and the capacity is about one tenth of what is theoretically possible.

This is ascribed to the poor electrical conductivity of the poly(carbon monofluoride).

These high amounts of carbon black needed for improved electrical conductivity, or reduced impedance of the battery, diminish the capacity per unit volume of the battery as less manganese dioxide can be employed per unit volume of the positive paste mix.

The carbon particle anodes tend to have poor mechanical strength leading to fracture under conditions of vibration and mechanical shock.

Materials such as lithium manganese oxide for cathodes and silicon particles for anodes exhibit much lower practical specific capacity than theoretically available.

Impurities, such as non-lithium salts, iron, and manganese to name a few, with the binder can also be highly deleterious to battery performance.

Commercially available carbon nanotubes such as NC7000™ (Nanocyl) or Graphistrength® (Arkema) can contain as much as ten percent or more by weight of residual metal catalysts and are not considered advantageous for batteries at these levels of impurity.

During the burning off of the polymer and cooling the lines can crack due to shrinkage forces and so increase impedance.

The low ionic conductivities of polymer and inorganic solid electrolytes are presently a limitation to their general use in energy storage and collection devices.

Alkaline batteries are known to have significantly poorer capacity on high current discharge than low current discharge.

One of the most serious drawbacks of the present DSSCs technology is the use of liquid and corrosive electrolytes which strongly limit their commercial development.

Replacement of the presently used electrolytes is desirable, but candidate electrolytes have poor ion transport.

However, utilization of carbon nanotubes in these applications has been hampered due to the general inability to reliably produce higher-surface area carbon nanotubes and the ability to disperse carbon nanotubes in a matrix.

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